Table 1.

Cross aldol reaction of ethyl (benzoylphenyl)phosphinate (5a) and acetone (6a) catalyzed by L-proline derivatives^a

entry	catalyst	loadingb	solvent	yield (%)c	ee (%)d		7a/8ae
					7a	8a
1f	1	10	acetone	93	72	47	55:45
2f	2	10	acetone	63	45	28	58:42
3f	3	10	acetone	83	82	62	54:46
4f	4	20	acetone	89	95	74	53:47
5	4	20	THF	90	95	67	52:48
6	4	20	CH2Cl2	79	94	65	50:50
7	4	20	DMSO	81	52	32	48:52
8	4	20	DMF	81	69	39	58:42
9g	4	20	acetone	87	91	59	59:41
10f,h	4	20	acetone	58	99	91	52:48

^aUnless otherwise indicated, all reactions were carried out with the ketophosphinate 5a (0.50 mmol), acetone (0.5 mL), and the catalyst in the specified solvent (1.0 mL) at rt for 24 h.

^bmol %.

^cTotal yield of the inseparable diastereomers (7a and 8a) isolated after column chromatography.

^dDetermined by HPLC analyses.

^eThe ratio of 7a/8a; determined by ¹H NMR analyses.

^f2.0 mL of acetone was used.

^gIonic liquid 1-butyl-3-methylimidazolium terafluoroborate (300 mg) was added.

^hCarried out at -30 °C for 96 h.